You’ve probably heard this one before, but since I also get newbie writers reading my blog, I’m going to go for it: there’s such a thing as too many or too few deaths and there are times when a character shouldn’t die.
Now, for a short elaboration.
If you are going for a cutesy Romance, then killing off half of your secondary characters and one of your MCs is a no-no; if you are writing an action-packed mafia novel, then no one dying is a no-no.
What I mean to say is that the deaths in your book must make sense. They shouldn’t be there because of shock value or because you got bored with a character; there should be meaning behind them such as raising the stakes, the emotional downfall of someone who loved the deceased character or people bonding in their grief.